Length of Last Word

Given a string s consists of upper/lower-case alphabets and empty space characters ' ', return the length of last word in the string.

If the last word does not exist, return 0.

Note: A word is defined as a character sequence consists of non-space characters only.

For example, 
Given s = "Hello World",
return 5.

求字符串最后一个单词的长度

1. 之前考虑不全,　当只用一个length时,会出现'a '时判断错误,　于是要用两个标志来指明

2. 其实也可以先求长度,　从后往前就是求第一个单词的长度

class Solution {
public:
    int lengthOfLastWord(const char *s) {
        int length1  = 0;
        int length2  = 0;
        int i,j;
        char c;
        while(*s!='')
        {
            if(*s++!=' ') 
                length1++;
            else if(length1!=0)
            {
                length2 = length1; 
                length1 = 0;
            }
        }
        if(length1!=0)
            return length1;
        if(length1==0)
            return length2;
    }
};

这个是从尾到头,　直接求第一个单词长度,这样就是最后一个的长度了

有几点:

１.　const char *p如果不加const就会报错,　类型不一样

２.　s + lenght - 1; 这里要减１

class Solution {
public:
    int lengthOfLastWord(const char *s) {
       int length = strlen(s);
       int i;
       int len = 0;
       const char *p = s  + length - 1;
       while(length--)
       {
        if(*p!=' ')
        {
            len++;
            p--;
        }
        else if(len!=0)
                break;
            else
                {
                    p--;
                    continue;
                }
       }
        return len;
    }
};